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I picked up a couple of scraps of nicely quartered Doug Fir the other day, should make at least 4 tops, if I can resaw it cleanly enough.

It's nice looking stuff, and I've heard that it makes pretty good tops. Density is ..... holy cow. Almost 8 g/cu. inch!!! That's denser than anything else I've seen before.

Can't yet do any deflection tests, as it's still an inch thick.

What might I expect from this? Too dense? See if it dries out some over time, (reducing weight/measure of density)? Build with it, but quite thin?

If I do use it, what would you think? larger guitar or smaller guitar? Lighter wood for back/sides, or something dense, like Osage Orange?

Thanks!

I picked up a top from Larry Stamm a while back haven't used it yet - it's pretty sapping.

Here's what he told me about top thicknesses:

I typically aim for a thickness that is 10% - 15% thinner than I would
use for Engelmann spruce in the same application, and also use lighter
bracing. My aim is to get an equivalent flexibility of the finished
soundboard when compared with spruce or cedar, but the fir always ends
up being a bit heavier.

I used to try to get the equivalent flexibility in the unbraced
soundboard, but the thickness just got too thin and fragile then. By
leaving the fir a bit thinner and cutting back on the bracing
stiffness, it seems to work just as well but the finished instrument
is more robust.

Neil

I'm working with a similar species (hemlock) quarter sawn, fine grain, clear, batch 150bf that I got last month. I milled and joined top down to .80 and it's still very stiff length wise....but laterally has good a wobble to it and taps nice. I'm still experimenting to reduce thickness and test! This top has been standing free for 3 weeks and no warping or cupping. Very stable. I would expect the same from a good fir cut.
Since fir is a very structural wood and also a bit heavier, it WILL be necessary to make it thinner....and like Neil said, bracing can probably be reduced rather than reducing thickness to near nothing.
I plan to build a complete guitar out of my batch of hemlock...just for grins. Not too pretty...but neither am I.

Kent

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Well you can expect the following, don't mean it will all happen but this is common for fir.

These are all the things I have observed in tooling fir.

its heavy
it is prone to splintering...long nasty sharp splinters...especialy if there is runnout.
may have hidden pitch pockets
big contrast between hardness of the grain lines, the soft grain may sand out leaving the hard grain and a ripple corduroy effect. Best to be scraped, not sanded.
Water stains and water born finishes tend to accentuate this couduroying as well.
It does not take dark stain nicely...the hard / soft altering grains resist and or suck up the stain
Best to shellack it first and then tint the finish if you want to shift its colour.
Bends easy enough.

Me have used quartered, rift and flat sawn fir. Have used it for tops, backs sides and necks...have done complete builds with it, including a bowl back and a 2,600 sq ft. house, all the doors (raised panel) and trim work. Burns good too, keeping me warm in the winter.

For nice clear neck material, is best to look at the 2 x 12 x 14ft or longer stock...this is cut from lower down in the log and as such tends to be much clear.

After about a dozen or so builds with the stuff, my take for instruments is ... it makes for a good top and ok back and sides and necks. But it does get the job done and is a cheap or inexpensive wood.


blessings
the
Padma

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One of my last ones was DF. I took the top to .105. Turned out with a lot of sustain, rich tone but not a lot of throatiness if you know what I mean. It was on blk walnut which generally is not overly reponsive. The df did better than wrc on the walnut.
I plan to do another and when I do I was going to do the Symogyi .280 defection on it. It definatly could have been a thinner top.
I was told by Tim McKnight who also does some df that it can have tendancy to be a little splitty and he is right. Don't worry it splits very straight and is easy to fix.
Hope this helps. Let us know how it turns out.
Maybe I will post a pic.

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Mark Ewing
Columbus Ohio
"Trees are an important and precious thing. We should build good things with them. Building good guitars with heart are the best use for them." K. Yairi.

Thanks all - I appreciate the detailed responses.

I plan to use it for a top. So what I'm getting here is ... build it thinner, with lighter bracing, and watch out for killer splinters! OK - can do.

So, for a top that is denser, hence thinner, and more lightly braced, what do you think that would better lend itself to - larger guitar? Or smaller guitar?

Alan, if you're there - I think you talked about the advantages of lighter tops (and assuming correlation between density and stiffness to weight ration - as I think you said is frequently the case) what would you suggest using a dense DF top for? Thanks!

Good timing. Just re-sawed 5 sets of DF tops last week, first time with it....looking forward.

Gotta talk potential resin seepage. Anyone consider heating the wood (while stickered and clamped) to say 140 F or so to either release any resin or crystallize? Woodstove or oven or ? Only reason to state this is I've seen resin seep out in building framing after many months here on the west coast.

Guitar living envir. range is, say, 30-90 deg., 10-90 % hum., Sticker in oven 140 deg, 0% hum (to cover the range).?????? NO EXPERIENCE, JUST MY THINKING!!!!

p.s.-Not interested in 10 deg. 100% hum test

Look forward to DF photos of builds.

On the sap problem. The high end house I have been working on for my contractor friend used doug fir for almost everything even cabinets. To give you and idea the detached two car garage cost more that 1.2 million dollars to build on flat ground!!! It does have a small art studio above. All the wood is reclaimed. We had a door company make all the doors. They are beautiful but the door company had fits with unseen sap pockets that would show up days and some times weeks or months after the doors were made. They were freaking out and charging for it. This reclaimed wood did all kinds of weird things until the finish was put on. Mostly it just seemed to sweat a little sap stain in very small amounts in a way I have never seen before. The painters had to come along and wipe it down with lacquer thinner and resand in some areas. Once they got a finish on it the problem seemed solved. From what I observed I would think the guitar top is so thin you would have to be unlucky to have a major unseen sap pocket and even if you did once finished it would not move tword the finished top but in a worse case scenario would head for the unfinished inside. Douglas fir varies wildly, some is as heavy and dense as maple and some is lighter and softer than most spruces. The harder heaver stuff seems more prone to splits pealing up on their own and I wouldn't want to try building a guitar out of it. I have a good size piece like this that resides between the bone in my thumb and the base of my fingernail.

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I hear tell that cooking the top can set the pitch from running.

Never done did it but the dudes who really promote cooking tops
can be found over at http://www.luthierforum.com

Ask for Mario.

blessings

Padma

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Audiences and dispensations on Thursdays ~ by appointment only.


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On the topic of cooking tops...there have been reports here by quite a few who do so. I only cook tops that are dry to begin with...I wait until they've been in my shop for a year before even considering doing so. I have no experience with cooking freshly sawn or green tops. I made an aluminum flashing-lined Baltic birch oven for this and use a heating blanket as a heating source. I sticker 2-3 sets of spruce tops and weigh the stack down before closing the oven. I heat to 200-225*F for 2 to 4 hours. I open occasionally to let the steam escape. Todd Stock employs a food dessicator to his oven which I plan to employ as well. After the prescribed time I allow them to cool slowly before removal.

After a week of re-stabilizing, my measured weight loss is about 5-10%...I believe what's happening is that it's driving out some resin (lower MW?) and crystallizing other resin (higher MW?)...essentially an accelerated aging procedure. Some have theorized that it is also reducing or collapsing the cell structure which renders the plate denser and less likely to take on as much moisture as an unbaked plate. Bottom line...I like the dry feel and glassy tap tone of an oven-dried top...there's a difference IMO.

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JJ
Napa, CA
http://www.DonohueGuitars.com

As far as cooking tops, I cook mine at 200 F for an hour. These are tops that have already been dry. I just make sure to be close by when doing so, you never know...wood in the oven is pushing it.

Chuck

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